Bleaching artificial fatty acids



Patented Aug. 9, 1932 UNITED STATES PATENT oFFIcs WHEELM PUNGS, F LUD'WIGSHAFEN-ON-TEE-BHINE, GERMANY, ASSIGNOR TO I. G.

FABBENINDUSTRIE AKTIENGESELLSCHAFT, OF FBANKFOBT-ON THE MAIN, GER- Em, A CQEPORATION OF GERMANY BLEACEING ARTIFICIAL FATTY ACIDS Ho Drawing. Application filed Kay 2, 1928, Serial No. 274,673, and in Germany May 20, 1927.

1 have found that the crude artificial fatty acids which'means acids obtained by the oxidation with the aid of air or similar gaseous oxidizing agents containing oxygen 0t higher hydrocarbons of the parafiiu series, or crude oxidation products containing the same, which often possess a dark color and unpleasant smell, are converted into highgrade, pale and sweet smelling products by treatment with a solution of substances which give off or transfer oxygen, the said substances being hereinafter referred to for the sake of brevity as agents supplying oxygen. Numerous oxidizing agents such as chromic acid potassium permanganate, hydrogen peroxid and the like may be employed for this purpose. The employment of chromic acid in a medium previously acidified with another mineral acid or organic acid, other than those to be treated, has

proved to be extremely satisfactory.

The method of working when employing chromic acid consists, for example, in stirring the crude artificial fatty acids or crude products containing the same, with dilute sulfuric acid or a. solution of a chromic salt,

so as to establish a fine state of distribution,

heating the mixture, and then adding the amount of chromic acid solution requisite for bleaching, heating being continued. When the reaction is completed, the prod not is washed until free from chromium salts, and is then freed from water, for example by melting or by centrifuging.

The operation is preferably carried out at temperatures above 100 C. or example, the temperature is maintained at about 105 C. at the commencement of the bleaching and is raised to from 110 to 120 C. towards the end of the bleaching, and such rise in temperature may be established by concentratmg the bleaching solution during the process, or by working under pressure. The temperature must not however be so high as to lead to a decomposition of the fatty acid.

The process according to the present invention may be modified in any suitable way according to the bleaching agent selected.

The said agent may be added in the coldor warm condition and the bleachin may be carried on in stages, by adding on a portion of the re uisite amount of b caching agent at first, rawing off the spent solution,

then adding a further'quantity of the :fi'c sh oxidizing agent, and continuing in the same manner until the desiredbleaching effect has been produced. "When chromic acid is used for the bleaching it is advisable, in case it is desired to regenerate the acid by electrolytic means, to begin with a concentration which will be suitable for such regeneration. The artificial fatty acids, or'crude products containin the same, which are to be bleachedmay also be exposed to the action of the oxidizing agent after having been dissolved in a suitable solvent. Finally, the substances to be bleached may be subjected to a preliminary treatment with suitable solvents or absorbents and the like, or the bleached products may afterwards be treated with the said or similar agents, or both treatments may be beneficial.

By the treatment in accordance with the invention herein described, dark colored and malodorous artificial fatty acids, or crude products containing the same, are converted into light colored products of agreeable smell, which have an acid value of from about 200 to 27 0 and are of considerable value for the industries employing fatty acids and especially the soap industry.

The following examples will further illustrate the nature of the said invention which however is not limitedthereto.

Ewample 1 250 grams of the dark malodorous products obtainable by the oxidation of paraffin, for example by rousing with'air at an ele vated temperature in the presence of solid bodies, which may be inert, or which may have a catalytic action, are treated with 3 liters of a. 42 per cent sulfuric acid solution containing 100 grams of chromic acid, the mixture being stirred and heated to gentle ebullition. A concentrated aqueous solution (from 50 to 60 per cent strength) of 400 grams of chromic acid is then run in slowly, after which the reaction mixture is stirred oxidation tion vessel has been heated to about 90 C.-

solution, assisted b almost white pr uct is boiled twice with distilled water in the same manner, in order.

per cent sulfuric acid.

phuric aci for 4.- to 5 hours at from 105 to 110 C. and left at rest to cool down-slowly. The product separates out as a solid, slightly greenish colored cake, on the surface a of the aqueous solution. The traces of chromiumcompounds contained in the reaction product are extracted by boilin to 1.5 liters of a 10 per cent sul uric acid energetic stirring. The

to eliminate any residual traces of sulfuric acid. The resulting productis almost white and of agreeable smell reminiscent of cocoanut fat. I

Ema/mple .2

I 375 grams of theoxidation product from parafiin, obtainable by rousing parafiin with air at an elevated temperature in the presence of solid bodies, which may be inert, or which may have a catalytic action, are emulsified by stirring into 4.5 liters of gentl boiling 42 A big 1y concentrated aqueous solution of 540 grams of potassium permanganate is run into the boiling reaction mixture in the course of two hours, and the mixture is he t stirred at a temperature above 100 C. or from 2 to 3 hours. When the reaction is completed, the parafiin oxidation roduct is treated with dilute suld as in Example 1. Any traces of manganese dioxid present in the resulting product ma be removed by melting the prodnot while a din an adsorbent, such as bleachin earth, filterm the hot mixture after carefu 1y stirring it, the manganese dioxide bein adsorbed by the bleaching earth and retaine on the filter. 'Ihe'resultmg. product has the same character as that obtained according to Example 1. Example 3 I A lead reaction vessel is charged with sul furic a'cd of 40 per cent strength containing ams of chromic sulfate per liter. The sai lead vessel serves as an anode and isconnected with the positive pole of a source of electric current. The cathode may consist of any metal which is stable against the action of the electrolyte for example of lead, and preferably has the form of a stirrer. After the solution contained in the said reacso much of an oxidation product of araflin obtainable by rousing the said para with with 1 fin described in Example hydrocarbons of the para 11 possible to above 100 C. and the current density is reduced somewhat towards the end of the bleaching process which requires from 4 to 10 hours depending on the degree of oxidation of theinltial material.

When the said oxidation products of parafhave been sufiicientl bleached, the current is switched off, an the stirrer brought to rest whereupon the bleached products separate cut from'the liquid. The bleached product which is pale green .in color is drawn off 'while still hot and worked up as described in Example 1. The product which has thus been purified has a similar consistency to that What-I claim is:

1. A process for bleaching crude substances obtained by the destructive oxidation of high molecular paraflins and containing artificial fatty acids, and obtained by oxidizing higher hydrocarbons of the parafiin series with gases containing oxygen which comprises treatin the said crude substances with a solution 0 agents supplying oxygen while warming to at least 100 O.;but not sohigh as to' lead to a decompositionof the fatty acids.

2. A process for bleaching crude substances obtained by the destructive oxidation of high molecular paraflins and containing artificial fatty acids and obtained b' oxidizing higherseries with gases containing oxygen, which comprises treating these with a solution of agents supplying oxy- I gen at temperatures above 100 C. but not so higi as to lead to a decomposition of the fatty aci s. v

3. A process for bleaching a crude malodorous brown oxidation product of paraffin containing artificial fattv acids and obtained by treating plaraflin with gases containing oxygen whic comprises treating the said product with a solution of chromic acid in aqueous sulfuric acid at a temperature of from to 110 C.

In testimony whereof I have hereunto set my hand. I

, WILHELM PUNGS.

air at an elevated temperature in the pres-v I ence of solid bodies which may be inertv or have catalytic action, is added thereto with energetic stirring that about 80 the said oxidation roduct are intro need for each liter of the so ution and the electric circuit is then connected. The voltage employed is about 3 to 5 volts and the current density amounts to about 500 amperes per square meter. The temperature is slowly raised if ams of 

